As various types of Internet services are provided and the frequency of use of the Internet increases, Internet crimes leaking personal information on users using the Internet frequently occur. Accordingly, various types of security systems and methods have been developed and sold to prevent the leakage of the personal information stored in a client personal computer (PC).
However, in a case where a client is forged or appropriated in an environment in which clients and servers are connected through a network (referred to as a “CS environment”) in an information system using the Internet, a corresponding server may transmit critical personal information stored in the server to the forged or appropriated client without suspicion. In this case, the conventional security system for protecting the personal information is useless.
Particularly, in a case where a malicious code such as a game hacking tool disrupts a client program in an online game, game rules are collapsed, and a fair play cannot be maintained, so that there is a problem in that gainers may lose interest in the game. For example, problems occur due to a Non-Client Bot in an online game. Accordingly, the number of gamers reduces, and this causes economical losses of game providers providing online game services.